Travel control apparatuses for automatically performing lane change of a vehicle have been conventionally known. Such a travel control apparatus may use a known technique of determining whether or not a space for lane change exists in an adjacent lane to the lane in which the subject vehicle travels and executing the lane change when the space for lane change exists in the adjacent lane (see WO2010/082353).
The above conventional technique does not take into account the control when the space for lane change becomes small halfway the lane change. In such a case, the vehicle may not be appropriately controlled.